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Remote Sensing of Mangrove Forests in an Environment of Global Change
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
LAI: LAI is the leaf area per unit ground area. It indicates how many leaf (or photosynthetically active) surfaces are in a column extended from, the ground area under the canopy diameter, up through the canopy. It can be estimated from NDVI as: LAIi=LAImax×(NDVIi−NDVImin)(NDVImax−NDVImin)
Satellite Guided Agriculture: Soil Fertility and Crop Management
Published in K. R. Krishna, Push Button Agriculture, 2017
Reports from Chinese wheat producing zones indicate that satellite imagery could be adopted to trace the growth and monitor increase of leaf area index of a wheat crop. For example, Xiaoyu et al. (2014) have reported that, in case of winter wheat grown around Beijing area, satellite techniques were useful in showing LAI increase. Satellite images from a 3500 ha field showed that between April and May, LAI increased by less than 1 within 14% of field area. About 64% area showed LAI increase between 1 and 2, and 20% area showed LAI increase of about 2. It is suggested that LAI increase could be used as indicative of crop growth. Therefore, satellite-guided monitoring of wheat growth is possible. Further, Song et al. (2010) have shown that in the wheat belt, satellite imagery could also be adopted to monitor uniformity of wheat crop growth. Remote sensing allows farm-ers to screen a very large area of wheat belt for uniformity and other char-acteristics, in one stretch, using high-resolution imagery. For example, they used images from ‘QuickBird’ high-resolution sensors to study wheat crop at various stages of growth from seedling to booting and then until senescence of leaves. It seems wheat crop growth data at boot leaf stage provides important information about grain yield, since it is positively cor-related with grain production. The correlation coefficient between OSAVI (Optimized Soil Adjusted Vegetative Index) with wheat grain yield was 0.651 (R2). The GNDVI (Greenness-Normalized Vegetative Index) was negatively correlated with grain protein content. It is opined that satellite imagery procured from agencies connected with QuickBird or other satellites could be used by farmers to trace wheat growth and assess grain productivity and quality.
Winter wheat leaf area index inversion by the genetic algorithms neural network model based on SAR data
Published in International Journal of Digital Earth, 2022
Xiaoping Lu, Xiaoxuan Wang, Xiangjun Zhang, Jun Wang, Zenan Yang
The leaf area index (LAI) is an important vegetation structure parameter in the biogeochemical cycle (Katsuhama et al. 2018; Le Maire et al. 2012; Prévot, Champion, and Guyot 1993). In this paper, LAI was defined as half of the sum of the total leaf area per unit surface area (Ren et al. 2018). LAI is an important index for estimating vegetation coverage, monitoring and forecasting crop growth, biomass, yield, etc. Therefore, the rapid and accurate inversion of LAI is of great research significance for agricultural monitoring and biogeochemical cycles.
Reduction of energy consumption in residential buildings with green roofs in three different climates of Iran
Published in Advances in Building Energy Research, 2020
Energy exchange of vegetation layer and the atmosphere is calculated from the following equation (Frankenstein & Koenig, 2004):In the above equation, Ff is the net heat flux into the vegetation layer (W/m2), αf is the air inside the layers of foliage, σf is the vegetation fraction, Iir↓ is the longwave radiation received (W/m2), Is↓ is the solar flux at ground per unit (W/m2). Tf is the plant's surface temperature (K), Tg is the ground's temperature (K), Hf is the plant sensible heat flux per unit (W/m2), Lf is the Plant latent heat flux (W/m2), ϵf is emittance power of foliage with the value 0.95. εg is issuing power of foliage with the value 0.98. εf − εf + εg = ε1 (Frankenstein & Koenig, 2004). In addition to the latent and sensible heat transfer, this equation contains the heat transfer for short- and long-wavelength radiation absorbed by plants with multiple radiations. The terms latent and sensible heat transfer (Hf and Lf) are somewhat complex will be elaborated in details, below: the sensible heat transfer between the medium and the plant (Hf) is affected by the temperature difference between them, the wind speed, and LAI. LAI is dimensionless and as noted earlier; it is the ratio of area under the plant per unit of area, whose value ranges from 0.5 to 5. The σf or vegetation fraction is the ratio of the roof shade by the vegetation to the total area of the roof and e0 is the coefficient for the sensible heat (W/m2).
Evaluating the Economic Water Productivity underfull and deficit irrigation;the case of sesamecrop (Sesumum indicum L.)in woreda Kafta-Humera,Tigrai-Ethiopia
Published in Water Science, 2019
The LAI-2000 Plant Canopy Analyzer was used in measuring for determination of LAI (leaf area index). And Canopy cover (CC) was estimated from the different irrigation treatment in the season based on Raes et al. (Equation 2).